org.apache.commons.beanutils

Class BeanToPropertyValueTransformer

java.lang.Object

org.apache.commons.beanutils.BeanToPropertyValueTransformer

All Implemented Interfaces:

org.apache.commons.collections.Transformer

public class BeanToPropertyValueTransformer
extends Object
implements org.apache.commons.collections.Transformer

Transformer that outputs a property value.

An implementation of org.apache.commons.collections.Transformer that transforms the object provided by returning the value of a specified property of the object. The constructor for BeanToPropertyValueTransformer requires the name of the property that will be used in the transformation. The property can be a simple, nested, indexed, or mapped property as defined by org.apache.commons.beanutils.PropertyUtils. If any object in the property path specified by propertyName is null then the outcome is based on the value of the ignoreNull attribute.

A typical usage might look like:

 // create the transformer
 BeanToPropertyValueTransformer transformer = new BeanToPropertyValueTransformer( "person.address.city" );

 // transform the Collection
 Collection peoplesCities = CollectionUtils.collect( peopleCollection, transformer );
 

This would take a Collection of person objects and return a Collection of objects which represents the cities in which each person lived. Assuming...

• The top level object in the peeopleCollection is an object which represents a person.
• The person object has a getAddress() method which returns an object which represents a person's address.
• The address object has a getCity() method which returns an object which represents the city in which a person lives.

Version:

$Id$

See Also:

PropertyUtils, Transformer

Constructor Summary

Constructors

Constructor and Description
BeanToPropertyValueTransformer(String propertyName) Constructs a Transformer which does not ignore nulls.
BeanToPropertyValueTransformer(String propertyName, boolean ignoreNull) Constructs a Transformer and sets ignoreNull.

Method Summary

Modifier and Type	Method and Description
String	getPropertyName() Returns the name of the property that will be used in the transformation of the bean.
boolean	isIgnoreNull() Returns the flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.
Object	transform(Object object) Returns the value of the property named in the transformer's constructor for the object provided.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BeanToPropertyValueTransformer

public BeanToPropertyValueTransformer(String propertyName)

Constructs a Transformer which does not ignore nulls. Constructor which takes the name of the property that will be used in the transformation and assumes ignoreNull to be false.

Parameters:

propertyName - The name of the property that will be used in the transformation.

Throws:

IllegalArgumentException - If the propertyName is null or empty.

BeanToPropertyValueTransformer

public BeanToPropertyValueTransformer(String propertyName,
                                      boolean ignoreNull)

Constructs a Transformer and sets ignoreNull. Constructor which takes the name of the property that will be used in the transformation and a boolean which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.

Parameters:

propertyName - The name of the property that will be used in the transformation.

ignoreNull - Determines whether null objects in the property path will genenerate an IllegalArgumentException or not.

Throws:

IllegalArgumentException - If the propertyName is null or empty.

Method Detail

transform

public Object transform(Object object)

Returns the value of the property named in the transformer's constructor for the object provided. If any object in the property path leading up to the target property is null then the outcome will be based on the value of the ignoreNull attribute. By default, ignoreNull is false and would result in an IllegalArgumentException if an object in the property path leading up to the target property is null.

Specified by:

transform in interface org.apache.commons.collections.Transformer

Parameters:

object - The object to be transformed.

Returns:

The value of the property named in the transformer's constructor for the object provided.

Throws:

IllegalArgumentException - If an IllegalAccessException, InvocationTargetException, or NoSuchMethodException is thrown when trying to access the property specified on the object provided. Or if an object in the property path provided is null and ignoreNull is set to false.

getPropertyName

public String getPropertyName()

Returns the name of the property that will be used in the transformation of the bean.

Returns:

The name of the property that will be used in the transformation of the bean.

isIgnoreNull

public boolean isIgnoreNull()

Returns the flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not. If set to true then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged but not rethrown and null will be returned. If set to false then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged and rethrown.

Returns:

The flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.